Hydrorefining of petroleum crude oil and catalyst therefor



United States Patent 3,269,958 HYDROREFINING OF PETROLEUM CRUDE OIL ANDCATALYST THEREFOR John G. Gatsis, Des Plaines, 111., assiguor toUniversal Oil Products Company, Des Plaines, [1]., a corporation ofDelaware No Drawing. Filed Jan. 2, 1964, Ser. No. 335,353 11 Claims.(Cl. 252439) The invention herein described is adaptable to a processfor the hydrorefining of heavy hydrocarbon fractions and/or distillatesfor the primary purpose of eliminating or reducing the concentration ofvarious contaminants therein. More particularly, the present inventionis directed toward a catalytic hydrorefining process for effecting, in asingle operation, the substantial removal of various types of impuritiesfrom heavy hydrocarbon charge stocks, and is especially advantageous intreating petroleum crude oils and topped, or reduced crude oils for theremoval of organo-metallic contaminants and the conversion ofpentane-insoluble asphaltenic material.

Petroleum crude oils, and topped or reduced crude oils, as well as otherheavy hydrocarbon fractions and/ or distillates including black oils,heavy cycle stocks, visbreaker liquid effluent, etc., are contaminatedby the presence of excessive concentrations of various non-metallic andmetallic impurities which detrimentally affect various processes towhich such heavy hydrocarbon mixtures may be subjected. Among thenon-metallic impurities are nitrogen, sulfur and oxygen which exist isheteroatomic compounds in relatively large quantities. Nitrogen isprobably most undesirable because it effectively poisons variouscatalytic composites which may be employed in the conversion ofpetroleum fractions; in particular, nitrogen and nitrogenous compoundsare known to be extremely effective hydrocracking suppressors.Therefore, it is particularly necessary that nitrogenous compounds beremoved substantially completely from all catalytic hydrocracking chargestocks. Nitrogenous and sulfurous compounds are further objectionablebecause combustion of fuels containing these impurities results in therelease of nitrogen and sulfur oxides which are noxious, corrosive andpresent a serious problem with respect to pollution of the atmosphere.In regard to motor fuels, sulfur is particularly objectionable becauseof odor, gum and varnish formation and significantly decreased leadsusceptibility.

In addition to the foregoing described contaminating influences,petroleum crude oils and other heavy hydrocarbonaceous material containhigh molecular weight asphaltenic compounds. These are non-distillable,oilinsoluble coke precursors which may be complexed with sulfur,nitrogen, oxygen and various metals. Generally, the asphaltenic materialis colloidally dispersed within the crude oil, and, when subjected toheat, as in a vacuum distillation process, have the tendency toflocculate and polymerize whereby the conversion thereof to morevaluable oil-soluble products becomes extremely difficult. Thus, in theheavy bottoms from a crude oil vacuum distillation column, thepolymerized asphaltenes exist as solid material even at ambienttemperatures; such a product is generally useful only as road asphalt,or as an extremely low grade fuel when out with distillate hydrocarbonssuch as kerosene, light gas oil, etc.

Of the metallic contaminants, those containing nickel and vanadium aremost common although other metals including iron, copper, lead, zinc,etc., are often present. These metallic contaminants, as well as others,may be present within the hydrocarbonaceous material in a variety offorms; they may exist therein as metal oxides or sulfides, introducedinto the crude oil as metallic scale or particles; they may be in theform of soluble salts of such metals; usually, however, the metalliccontaminants are ice found to exist as o-rgano-metallic compounds ofrelatively high molecular weight, such as metallic porphyrins and thevarious derivatives thereof. Where the metallic contaminants are presentas oxide or sulfide scale, they may be removed, at least in part, by arelatively simple filtering technique, the water-soluble salts beingremovable by washing and subsequent dehydration of the crude oil. Aconsiderable quantity of the organo-metallic complexes, however, arelinked with asphaltenic material and become concentrated in the residualfraction; other organo-metallic complexes are volatile, oil-soluble andare, therefore, carried over in the lighter distillate fraction. Areduction in the concentration of the organo-metallic complexes is noteasily achieved, and to the extent that the crude oil, reduced crudeoil, or other heavy hydrocarbon charge stock becomes suitable forfurther processing Notwithstanding that the concentration of theseorgano-metallic compounds may be relatively small in distillate oils,for example, often less than about 10 ppm. (calculated as if themetallic complex existed as the elemental metal), subsequent processingtechniques are adversely affected thereby. For example, when ahydrocarbon charge stock containing organo-metallic compounds, such asmetal porphyrins, in amounts above about 3.0 p-.p.m., is subjected tohydrocracking or catalytic cracking for the purpose of producinglower-boiling components, the metals become deposited upon the catalyst,increasing in concentration as the process continues. Since vanadium andthe irongroup metals favor hydrogenation activity, at crackingtemperatures, the resulting contaminated hydrocracking or crackingcatalyst produces increasingly excessive quantities of coke, hydrogenand light hydrocarbon gases at the expense of more valuable normallyliquid hydrocarbon products. Eventually the catalyst must be subjectedto elaborate regenerative techniques, or more often be replaced withfresh catalyst. The presence of excessive quantities of organo-metalliccomplexes adversely affects other processes including catalyticreforming, isomerization, hydrodealkylation, etc. With respect to aprocess for hydrorefinin-g, or treating of hydrocarbon fractions and/ordistillates, the presence of large quantities of asphaltenic materialand organo-metallic compounds interferes considerably with the activityof the catalyst with respect to the destructive removal of thenitrogenous, sulfurous and oxygenated compounds, which function isnormally the easiest for the catalytic composite to perform to anacceptable degree. Therefore, it is highly desirable to produce ahydrocarbon mixture substant-ially free from asphaltenic material andorgano-metallic compounds, and which mixture is substantially reducedwith respect to nitrogen and sulfur concentration.

The necessity for the removal of the foregoing contaminating influencesis well known to the possessing skill within the art of petroleumrefining processes. Heretofore, in the field of catalytic hydrorefining,two principal approaches have been advanced: liquid-phase hydrogenationand vapor-phase hydrocracking. In the former type of process, the oil ispassed upwardly in liquid phase, and in admixture with hydrogen, into afixed-bed or slurry of subdivided catalyst; although perhaps effectivein removing at least a portion of oil-soluble organometallic complexes,this type process is relatively ineffective with respect tooil-insoluble asphaltenes which are colloidally dispersed within thecharge, with the consequence that the probability of effectingsimultaneous contact betwen catalyst particle and asphaltene molecule isremote. Furthermore, since the hydrogenation reaction zone is generallymaintained at an elevated temperature, the retention of unconvertedasphaltenes, suspended in a free liquid phase oil for an extended periodof time, will result in flocculation making conversion thereofsubstantially more difficult. The rate of diffusion of the oilinsolubleasphaltenes is substantially lower than that of dissolved molecules ofthe same molecular size; for this reason, the fixed-bed processes, inwhich the oil and hydrogen are passed in a downwardly direction, arevirtually precluded. The asphaltenes, being neither volatile nordissolved in the crude, are unable to move to the catalytically activesites, the latter being obviously immovable. Furthermore, the efiiciencyof hydrogen to oil contact obtainable by bubbling hydrogen through anextensive liquid body is relatively low. On the other hand, vapor phasehydrocracking is carried out either with a fixed-bed or expanded-bedsystem at temperatures substantially above about 950 F.; while thisobviates to a certain extent the drawbacks of liquid-phasehydrogenation, it is not entirely well-suited to treating crude andheavy hydrocarbon fractions due to the high production of coke andcarbonaceous material, with the result that the catalytic compositesuccumbs to relatively rapid deactivation; this requires high capacitycatalyst regeneration equipment in order to implement the process on acontinuous basis.

Selective hydrocracking of a full boiling range charge stock is noteasily obtained, and excessive amounts of light gases are produced atthe expense of the more valuable normally liquid hydrocarbon product;also, when processing a petroleum crude oil, an indeterminate minimumquantity of cracked gasoline production is unavoidable, and such aresult is not desirable where the object is to maximize the productionof middle and heavy distillates such as jet fuel, diesel oil, furnaceoils, and gas oils.

A wide variety of heavy hydrocarbon fractions and/or distillates may betreated, or decontaminated effectively through the utilization of theprocess of the present invention. Such heavy hydrocarbon fractionsinclude full boiling range crude oils, topped or reduced crude oils,atmospheric distillates, visbreaker bottoms product, heavy cycle stocksfrom thermally or catalytically-cracked charge stocks, heavy vacuum gasoils, etc. The present process is particularly well adaptable to theprocess of hydrorefining of petroleum crude oil, and topped or reducedcrude oil, containing large quantities of pentaneinsoluble asphaltenicmaterial and organo-metallic compounds. A full boiling range crude oilis a preferred charge stock since the oil-insoluble asphaltenicmaterial, being in its native environment, is colloidally dispersed, andthus more readily converted to oil-soluble hydrocarbons. The asphaltenicmaterial in a reduced or topped crude oil has become agglomerated to acertain extent by reason of the reboil temperature of fractionation, andis, therefore, more difficult to convert. For example, a Wyoming sourcrude oil, having a gravity of 23.2 API at 60 F., not only is highlycontaminated by the presence of 2.8% by weight of sulfur, 2,700 p.p.m.of total nitrogen, approximately 100 p.p.m. of metallic complexes,computed as elemental metals, but also contains a high boiling,pentane-insoluble asphaltenic fraction in an amount of 8.4% by weight.Similarly, and a much more difficult charge stock to convert into usefulliquid hydrocarbons is a crude tower bottoms product having a gravity,API at 60 F., of 14.3, and contaminated by the presence of 3.0% byweight of sulfur, 3,830 p.p.m. of total nitrogen, 85 p.p.m. of totalmetals and about 10.93% by weight of asphaltenic compounds. Asphaltenicmaterial is a high molecular weight hydrocarbon mixture having thetendency to become immediately deposited within the reaction zone andother process equipment, and onto the catalytic composite in the form ofa gummy, high molecular weight residue. Since this in effect constitutesa large loss of charge stock, it is economically desirable to convertsuch asphaltenic material into pentane-soluble liquid hydrocarbonfractions. Furthermore, the presence of excessive quantities ofasphaltenes and organo-metallic contaminants appear to inhibit theactivity of the catalyst in regard to the destructive removal of sulfurand nitrogen.

In addition to the foregoing described contaminating influences, theheavier hydrocarbon fractions and or distillates contain excessivequantities of unsaturated compounds consisting primarily of highmolecular weight monoand di-olefinic hydrocarbons. At the operatingconditions normally employed to effect successful hydrorefining, as wellas a suitable degree of hydrocracking, the monoand di-olefinichydrocarbons have the tendency to polymerize and co-polyrnerize, therebycausing deposition of additional high molecular weight, gummypolymerization products within the process equipment and onto thecatalytic composite. Similarly, in processes for effecting the catalytichydrocracking of such heavier hydrocarbon fractions into lower-boilinghydrocarbon products, the catalytic composite becomes deactivatedthrough carbonization effected as a result of the deposition ofagglomerated pentane-insoluble asphaltenes, whereby the catalyticallyactive centers and surfaces of the catalyst are effectively shieldedfrom the material being processed.

The object of the present invention is, therefore, to provide a processfor hydrorefining heavy hydrocarbonaceous material, and particularlyfull boiling range crude oils, and topped or reduced crude oils,utilizing a catalytic composite prepared in a manner which makes itparticularly adaptable to the hydrorefining of such charge stocks. Thepresent invention affords the utilization of a fixed-bed hydrorefiningprocess, which, as hereinbefore set forth, has not been consideredfeasible due to the deposition of coke and other gummy carbonaceousmaterial. Although the difficulties encountered in a fixed-bed catalyticprocess are at least partially solved by a moving-bed or slurryoperation wherein the finely-divided catalytic composite is intimatelyadmixed with the hydrocarbon charge stock, the mixture being subjectedto the desired operating conditions, the slurry process tends to resultin a high degree of erosion, thereby causing plant maintenance andreplacement of process equipment to be diflicult and expensive.Furthermore, the slurry operation has the disadvantage of havingrelatively small amounts of catalyst being admixed with relatively largequantities of asphaltenic material, since it is difficult to suspendmore than a small percentage of catalyst within the crude oil. In otherwords, too few catalytically active sites are made available forimmediate reaction, with the result that the asphaltenic material hasthe tendency to undergo thermal cracking which results in largequantities of light gases and coke. These difficulties are in turn atleast partially avoided through the utilization of a fixed-fluidizedprocess in which the catalytic composite is disposed within a confinedreaction zone, being maintained, however, in a fluidized state byexceedingly large quantities of a fast-flowing hydrogen-containing gasstream. Difiiculties attendant the fixed-fluidized type process residein a large loss of catalyst, removed from the reaction zone with thehydrocarbon product effluent, the relatively large quantities ofcatalyst necessary to effect proper contact between the asphaltenicmaterial and active catalyst sites, etc. The process of the presentinvention makes use of a particularly prepared hydrorefining catalystutilizing a refractory inorganic oxide carrier material, which catalystpermits effecting the process in a fixed-bed unit without incurring thedeposition of exceedingly large quantities of coke and other heavyhydrocarbonaceous material. The present process and catalyst yields aliquid hydrocarbon product which is more suitable for further processingat more severe conditions required to produce a virtually completecontaminant-free hydrocarbon product. The process of the presentinvention is particularly advantageous in effecting the removal oforgano-metallic compounds, while simultaneously convertingpentane-insoluble material into pentane-soluble liquid hydrocarbons.

In a broad embodiment, therefore, the present invention relates to amethod of preparing a hydrorefining cata,-

lyst which comprises the steps of: (a) initially forming a refractoryinorganic oxide carrier material, and calcining said carrier material ata temperature above about 300 C.; (b) impregnating the calcined carriermaterial with a decomposable organometallic complex of a metal selectedfrom the group consisting of the metals of Groups VB, VI-B and VIII ofthe Periodic Table; (c) drying the impregnated carrier at a temperaturebelow about 150 C. and at which temperature the decomposition of saidcomplex is avoided; and, (d) thereafter decomposing said complex in thepresence of a hydrocarbon.

Another embodiment of the present invention provides a method forpreparing a hydrorefining catalyst which comprises the steps of: (a)initially forming an aluminacontaining refractory inorganic oxidecarrier material, and calcining said carrier material at a temperatureabove about 300 C.; (b) impregnating the calcined carrier material witha decomposable organo-metallic complex of a metal selected from thegroup consisting of the metals of Group VB, VI-B and VIII of thePeriodic Table; (c) drying the impregnated carrier material at atemperature within the range of from about 100 C. to about 150 C., andat which temperature the decomposition of said complex is avoided; and,(d) thereafter decomposing said complex at a temperature Within therange of from about 150 C. to about 310 C., and in the presence of ahydrocarbon boiling at a temperature above about 650 F.

As hereinbefore set forth, the catalytic composite, prepared inaccordane with the method of the present invention, is particularlyadvantageous in a process for hydrorefining petroleum crude oils and theheavy hydrocarbon fractions usually derived therefrom. Therefore, thepresent invention encompasses a process for hydrorefining a hydrocarboncharge stock, which process comprises the steps of: (a) initiallycontacting said charge stock with a catalytic composite of a refractoryinorganic oxide and at least one decomposable organo-metallic complex ofa metal selected from the group consisting of the metals of Groups VB,VIB and VIII of the Periodic Table; (b) decomposing said complex in thepresence of hydrogen sulfide and said charge stock at a temperatureabove about 150 C.; (c) increasing said temperature to a level aboveabout 3l0 C., and reacting said charge stock with hydrogen at a pressuregreater than about 500 p.s.i.g.; and, (cl) separating the total productefiluent to provide a hydrorefined normally liquid product.

A more limited embodiment of the present invention affords a process forhydrorefining an asphaltene-containing crude oil which comprises thesteps of: (a) initially preparing an uncalcined catalytic composite ofan aluminasilica carrier material and at least one decomposableorgano-metallic complex of a metal selected from the group consisting ofthe metals of Groups V-B, and VI-B and VIII of the Periodic Table; (b)decomposing said complex in the presence of hydrogen sulfide and saidcrude oil, and at a temperature within the range of from about 150 C. toabout 310 C.; (c) increasing said temperature to a level of from about310 C. to about 500 C. and reacting said crude oil with hydrogen in anamount of from about 5,000 to about 50,000 standard cubic feet perbarrel and at a pressure of from about 500 to about 5,000 p.s.i.g.; and,(d) recovering a hydrorefined liquid product substantially completelyfree from pentane-insoluble asphaltenes.

From the foregoing embodiments, it will be noted that the process of thepresent invention makes use of catalytically active metallic componentswhich are composited with a refractory inorganic oxide carrier material.It has been found that a catalyst comprising a porous, refractoryinorganic oxide carrier material, having a welldeveloped pore structure,has the ability to absorb a substantial quantity of the high-boilingasphaltenes while maintaining its activity with respect to the removalof organo-metallic compounds and the substantial reduction in theconcentration of nitrogen and sulfur. It has further been found thatconverted asphaltenes, that is, asphaltenes which have been hydrorefinedunder mild hydrogenative-cracking conditions, are an excellent solventfor the untreated asphaltenes which are, in and of themselves,pentane-insoluble and colloidally dispersed within the crude oil. Theuntreated asphaltenic material is much more readily converted wheninitially dissolved in such a solvent than when directly treated in adispersed phase suspended in a liquid carrier. Thus, by maintaining thefixed catalyst bed at mild hydrogenative-cracking conditions, or thosewhich preclude the thermal cracking of asphaltenic material, convertedasphaltenes will dissolve the incoming unconverted asphaltenes, therebymaking the latter more accessible to the catalytically active sites.This high degree of charge stock to catalyst contact is at least in partachieved through the use of a fixed-fluidized catalyst bed ashereinbefore set forth. However, as previously stated, there exists theneed for relatively large volumes of catalyst, in addition to greatquantities of fast-flowing hydrogen in order to maintain the catalyst inthe proper fluidized state. Through the use of the catalyst of thepresent invention, the need for relatively large volumes of catalyst,with respect to the volume of charge stock, and exceedingly largevolumes of fast-flowing hydrogen are substantially avoided. The catalystpreparation method, encompassed by the present invention, results inadditional catalytically active sites being made available not only forthe conversion of the incoming asphaltenes through absorption into thecatalyst, but also for the destructive removal of nitrogenous andsulfurous compounds.

As above noted, the present invention broadly involves contacting amixed phase heavy oil charge with hydrogen in the presence of anabsorptive hydrogenation catalyst under comparatively mildhydrogenation-hydrocracking conditions. The mild conditions, as hereinexpressed, are intended to be those operating conditions which minimizethe production of light gaseous hydrocarbons, coke, polymerizationproducts, other heavy carbonaceous material, etc. Thus, the catalyticcomposite is disposed as a fixed bed in a reaction zone, beingmaintained therein at a temperature in the range of from 725 F. to about785 F., and under an imposed pressure of from about 500 to about 5,000pounds per square inch gauge. At these operating conditions, the thermalcracking of asphaltenic material is inhibited and suppressed to theextent that the loss of liquid hydrocarbon product to gaseous wastematerial is significantly decreased, as is the deposition of coke andother heavy carbonaceous material. The particularly preferred operatingconditions include a temperature within the range of about 750 to about785 F. and a pressure of from about 1,000 to about 3,000 p.s.i.g.Hydrogen is employed in admixture with the charge stock in an amount offrom about 5,000 to about 50,000 s.c.f./bbl. The hydrogen-containing gasstream, herein sometimes designated as recycle hydrogen, since it isconveniently recycled externally of the hydrorefining zone, fulfills anumber of various functions: it serves as a hydrogenating agent, a heatcarrier, and particularly a means for stripping converted asphaltenicmaterial from the catalytic composite, thereby making still morecatalytically active sites available for the incoming, unconvertedasphaltenic material. Furthermore, the relatively high hydrogen tohydrocarbon mol ratio decreases the partial pressure of the oil vaporand increases vaporization of the oil at temperatures significantlybelow those at which thermal cracking of asphaltenes is effected. Theliquid hourly space velocity, herein defined as the volumes ofhydrocarbon charge per hour per volume of catalyst disposed within thereaction zone, will be at least partially dependent upon the physicaland chemical characteristics of the charge stock; however, the liquidhourly space velocity will normally lie within the range of from about0.5 to about 10.0, and preferably from about 0.5 to about 3.0.

The total product effluent from the hydrorefining zone is passed into ahigh-pressure separator maintained at about room temperature. Normallyliquid hydrocarbons are recovered from the separator, while thehydrogenrich gaseous phase is returned to the hydrorefining Zone inadmixture with additional external hydrogen required to replenish andcompensate for the net hydrogen consumption which may range from about200 to about 3,000 s.c.f./bbl. of charge, the precise amount beingdependent upon the characteristics of the charge stock. The recycledhydrogen-rich gas stream may be treated by any suitable means to effectthe removal of ammonia and hydrogen sulfide resulting from theconversion of nitrogenous and sulfurous compounds contained within thecharge stock. Furthermore, the normally liquid hydrocarbon product,removed from the high-pressure separator, may be introduced into astripping or fractionating column, or otherwise suitably treated for thepurpose of removing dissolved normally gaseous hydrocarbons, hydrogensulfide and ammonia.

An essential feature of the present invention resides in the methodemployed in the preparation of the catalytic composite disposed withinthe reaction zone. This hydrogenation catalyst can be characterized ascomprising a metallic component having hydrogenation activity, whichcomponent is composited with a refractory inorganic oxide carriermaterial of either synthetic, or natural origin, and which carriermaterial has a medium to high surface area and a well-developed porestructure. The precise composition and method of manufacturing thecarrier material is not considered to be an essential feature of thepresent invention, although the preferred carrier material, in order tohave the most advantageous pore structure, will have an apparent bulkdensity less than about 0.35 gram/co, and preferably within the range offrom about 0.10 to about 0.30 gram/cc. Suitable metallic componentshaving hydrogenation activity, are those selected from the groupconsisting of the metals of Groups V-B, VI-B and VIII of the PeriodicTable as indicated in the Periodic Chart of the Elements, FischerScientific Company (1953). Thus, the catalytic composite may compriseone or more metallic components from the group of vanadium, niobium,tantalum, molybdenum, tungsten, chromium, iron, cobalt, nickel,platinum, palladium, iridium, osmium, rhodium, ruthenium, and mixturesthereof. The catalyst may comprise any one or combination of any numberof such metals, an essential feature being the means by which themetallic component is ultimately combined with the refractory inorganicoxide carrier material. The concentration of the catalytically activemetallic component, or components, is primarily dependent upon theparticular metal as well as the characteristics of the charge stock. Forexample, the metallic components from Groups V-B and VI-B are preferablypresent in an amount within the range of about 1.0% to about 20.0% byweight, the iron-group metals in an amount within the range of about0.2% to about 10.0% by weight, whereas the platinum-group metals arepreferred to be present in an amount within the range of about 0.1% toabout 5.0% by weight, all of which are calculated as if the metalliccomponent existed within the finished composite as the elemental metal.

The refractory inorganic oxide carrier material may comprise alumina,silica, zirconia, magnesia, titania, boria, strontia, hafnia, andmixtures of two or more including silica-alumina, silica-zirconia,silica-magnesia, silica-titania, alumina-zirconia, alumina-magnesia,alumina-titania, magnesia-zirconia, titania-zirconia, magnesiatitania,silica-alumina-zirconia, silica-alumina-magnesia,silica-alumina-titania, silica-magnesia-zirconia,aluminasilica-magnesia, etc. It is preferred to utilize a carriermaterial containing at least a portion of alumina, and preferably acomposite of alumina and silica with alumina being in the greaterproportion. By way of specific examples, a satisfactory carrier materialmay comprise equimolar quantities of alumina and silica, or 63.0% byweight of alumina and 37.0% by weight of silica, or a carrier of 68.0%by weight of alumina, 10.0% by weight of silica and 22.0% by weight ofboron phosphate. In particular instances, the catalytic composite maycomprise additional components including combined halogen, andparticularly fluorine and/or chlorine, boric and/or phosphoric acid,etc. The refractory inorganic oxide carrier material may be formed byany of the numerous techniques which are rather well defined in theprior art relating thereto. Such techniques include the acid-treating ofa natural clay, sand or earth, coprecipitation or successiveprecipitation from hydrosols; these techniques are frequently coupledwith one or more activating treatments including hot oil aging,steaming, drying, oxidizing, reducing, calcining, etc. The porestructure of the carrier, commonly defined in terms of surface area,pore diameter and pore volume, may be developed to specified limits byany suitable means, for example, by aging the hydrosol and/or hydrogelunder controlled acidic or basic conditions at ambient or elevatedtemperature, or by gelling the carrier at a critical pH or by treatingthe carrier with various inorganic or organic reagents. An absorptivehydrogenation catalyst adaptable for utilization in the process of thepresent invention, will have a surface area of about 50 to about 700square meters per gram, a pore diameter of about 20 to about 300angstroms, a pore volume of about 0.10 to about 0.80 milliliter per gramand an apparent bulk density within the range of from about 0.10 toabout 0.35 gram/cc.

The catalyst is prepared by initially forming an alumina-containingrefractory inorganic oxide material having the foregoing describedcharacteristics. For example, an alumina-silica composite containingabout 63.0% by weight of alumina is prepared by the well-knowncoprecipitation of the respective hydrosols. The precipitated mate-rial,generally in the form of a hydrogel, is dried at a temperature of aboutC. and fora time sufficiently long to remove substantially all of thephysically-held water. The composite is then subjected to ahigh-temperature calcination technique in an atmosphere of air, for aperiod of about one hour :at a temperature above about 300 C., whichtechnique serves to remove the greater proportion of chemically-boundwater.

The calcined carrier material is combined with the catalytically activemetallic component, or components, through an impregnation techniquewhereby solutions of decomposable organo-metallic complexes of themetals selected from the group of the metals of Groups V-B, VI-B andVIII of the Periodic Table are employed. Suitable organo-metalliccompounds include molybdenum blue, molybdenum hexacarbonyl,phosphomolybdic acid, molybdyl acetlyacetonate, nickel acetylacetonate,dinitrito diamino platinum, dinitrito diamino palladium, silicomolybdicacid, tungsten hexacarbonyl, phosphotungstic acid, tungstenacetylacetonate, silicotungstic acid, tungsten ethyl xanthate, vanadiumcarbonyl, vanadyl acetylacetonate, phosphovanadic acid, vanadyl ethylxanthate, vanadium esters of alcohols, vanadium esters of mercaptans,nickel formate, various other carbonyls, heteropoly acids, beta-diketonecomplexes, etc. In those instances where the organo-metallic complex isnot watersoluble at the desired impregnation temperature, other solventsmay be employed and include alcohols, esters, ketones, aromatichydrocarbons, etc. The impregnated carrier material is then dried at atemperature less than about C., and preferably within the range of about100 C. to about 150 C. An essential feature of the catalyst preparationtechnique is that the impregnation and subsequent drying be carried outin a manner such that no decomposition of the organo-metallic complexoccurs; in other words, the dry, impregnated carrier material will havedistributed therein the decomposable organo-metallic compound.

The uncalcined, but dried, impregnated composite may be storedindefinitely until such time as it will be utilized in the hydrorefiningprocess, or it may be placed immediately in the reaction zone. After thecatalytic composite, containing the decomposable organo-metalliccomponent, or components, has been placed within the reaction zone, thetemperature thereof is increased to a level within the range of fromabout 150 C. to about 310 C. as the hydrocarbon charge stock isintroduced into the reaction zone. Thus, decomposition of theorgano-metallic compound, selected as the source of the catalyticallyactive metallic components, is effected in situ in the presence of ahydrocarbon. It is preferred that the decomposition be effected in thepresence of a hydrocarbon boiling substantially completely above atemperature of about 650 F., and it is particularly preferred to utilizethe charge stock which will ultimately be subjected to hydrorefiningconditions during the course of the process. It is further advantageousto conduct the decomposition of the organo-metallic compound in thepresence of hydrogen sulfide or a compound which yields hydrogen sulfideat a temperature within the aforesai-d range. Thus, a mercaptan such astertiary butyl mercaptan may be introduced into the reaction zone inadmixture with the charge stock, or the hydrogen sulfide may be suppliedas such in admixture with an inert gas including nitrogen, carbondioxide, argon, etc. The quantity of hydrogen sulfide, or mercaptan, issuch that the concentration of sulfur lies within the range of fromabout 0.01% to about 1.0% by Weight, based upon the total weight of thecatalytic composite disposed within the reaction zone. Notwithstandingthat the process is conducted in the presence of large quantities ofrecycle hydrogen, it is preferred to conduct the decomposition of theorgano-metall-ic compound in the absence of hydrogen and otherwell-known reducing agents.

Although the precise character of the catalytic composite, following thedecomposition in the presence of the hydrocarbon charge stock andhydrogen sulfide, is not known with accuracy, it is believed that themetallic component forms a new complex with the higherboilingasphaltenic compounds and the refractory inorganic oxide components ofthe catalyst. In any event, this particular method of effecting thedecomposition of the organo-metallic compound results in a catalyticcomposite having more catalytically active sites available to thepartially vaporized charge stock when the process is thereafterconducted at hydrorefining conditions hereinbefore set forth. Adecomposition temperature less than about 310 C. must necessarily beobserved in order to prevent an undue degree of premature thermalcracking of the catalytic composite.

Following the decomposition of the organo-metallic compound, hydrogen isintroduced at a predetermined rate Within the range of about 5,000 toabout 50,000 s.c.f./bbl. of hydrocarbon charge stock, and thetemperature is increased to a level within the range of from about 310C. to about 500 C., the pressure being increased to a level within therange of about 500 to about 5,000 p.s.i.g. The quantity of charge stockpassing through the reaction zone during the decomposition of theorgano-metallic complex is not wasted, but may be recycled andintroduced in the same manner as fresh hydrocarbon charge stock. Theprecise operating temperature and pressure, at any given instant, is atleast partially dependent upon the physical and chemical characteristicsof the hydrocarbon charge stock, the length of the period during whichthe catalyst has previously been functioning, and the desired endresult. In any event, it has been found beneficial to operate atconditions which inhibit or totally suppress the thermal cracking ofasphaltenic material.

As hereinbefore set forth, the asphaltenic material which has beenhydrorefined under mild hydrogenative conditions, precluding the thermalcracking thereof, is an excellent solvent for untreated asphaltenicmaterial which, in and of itself, is pentane-insoluble and colloidallydispersed within the crude oil charge. At least a portion of thehydrorefined asphaltenic material will be absorbed Within the catalyststructure, and will function as a solvent for unconverted asphaltenicmaterial introduced along with the hydrocarbon charge stock. The heavierliquid phase portion of the raw charge is absorbed into the catalystparticles, dissolved in the particle-held solvent, thereby acceleratingthe conversion by selective hydrocracking to additional solvent. Since asignificantly greater number of catalytically active sites have beenmade available to the charge stock, a significantly greater proportionof the incoming pentane-insoluble asphaltenic material will be convertedinto the more valuable pentanesoluble hydrocarbons. The recycle hydrogenstream, as hereinbefore set forth, serves to strip the convertedasphaltenes from the catalyst particles virtually immediately upon theformation thereof. Thus, the pentane-soluble hydrocarbons, resultingfrom the conversion of the asphaltenic material, are rapidly removedfrom the reaction zone, thereby eliminating the danger of anaccumulation of free liquid phase therein.

The following example is given for the purpose of illustrating themethod by which the process, encompassed by the present invention iseffected. The charge stocks temperatures, pressures, catalyst, rates,etc., are herein presented as being exemplary only, and are not intendedto limit the present invention to an extent greater than that defined bythe scope and spirit of the appended claims.

Example The charge stock utilized in illustrating the process of thepresent invention is a topped Wyoming sour crude oil. This sour crudeoil, having a gravity of 232 API at 60 F., is contaminated by thepresence of 2.8% by weight of sulfur, approximately 2,700 p.p.m. oftotal nitrogen, p.p.m. of metallic porphyrins (computed as if themetallic component existed as elemental nickel and vanadium), andcontains a high-boiling, pentane-insoluble asphaltenic fraction in anamount of 8.39% by Weight of the total crude oils. The topped crude oilindicates a gravity, API at 60 F, of 19.5, and contains 3.0% by weightof sulfur, 2,900 p.p.m. of total nitrogen, p.p.m. of nickel andvanadium, the pentane-insoluble asphaltenic fraction being about 8.5% byweight.

The catalytic composite is a spray-dried alumina-silica carrier materialcomprising about 63.0% by weight of alumina. The carrier material isprepared by initially precipitating, at a constant acidic pH of about8.0, a blend of acidulated water glass and aluminum chloride hydrosol,with ammonium hydroxide. The resulting hydrogel is washed free of sodiumions, chloride ions, and ammonium ions, and spray-dried. The spray-driedcomposite is oxidized, or calcined in an atmosphere of air for a periodof about one hour at a temperature of about 550 C. An impregnatingsolution is prepared utilizing isopropyl alcohol solutions of nickelacetylacetonate and molybdenum acetylacetonate in amounts required toproduce a final catalytic composite comprising 2.0% by weight of nickeland 16.0% by weight of molybdenum, calculated as if existing as theelements. The alumina-silica carrier material is impregnated with thealcoholic solution of the nickel and molybdenum complexes, and dried ata temperature of about 100 C. for a period of about two hours; thedrying temperature is controlled such that sudden temperature rises to alevel above about C., at which temperature the complex would decompose,is avoided.

The dried catalyst, having a particle size ranging from 20 to about 150microns, approximately 99.0% by weight thereof having a particle sizeless than 150 microns, is disposed as a fixed bed in a reaction zone,and in an amount of about 220 grams. The pressure within the reactionzone is increased to a level of 2,000 p.s.i.g., utilizing a stream ofnitrogen having been heated to a temperature of about 150 C. When theseconditions are reached, the nitrogen stream is admixed with the toppedcrude oil and hydrogen sulfide in an amount of about 1.0 mole percent,based upon the nitrogen stream. The normally liquid hydrocarbonefiluent, during this period of operation in which the nickel andmolybdenum acetylacetonate are being decomposed, is recycled to combinewith fresh feed, while the gaseous stream from the highpressureseparator is recycled after the addition thereto of suflicient hydrogensulfide to maintain the concentration to a level of about 1.0 molepercent. After a period of about two hours, the hydrogen stream replacesthe mixture of nitrogen and hydrogen sulfide, while the temperature isincreased to a level of about 350 C. The normally liquid producteffluent from the high-pressure separator is continuously recycled tocombine with fresh feed until such time as the quantity of hydrogenbeing recycled is about 25,000 s.c.f./bbl. of liquid charge, thetemperature has attained the desired operating level within the range ofabout 310 C. to about 500 C., and the recycle gas stream issubstantially free from nitrogen.

The reaction products from the reaction zone are continuously cooled andpassed into a high-pressure separator from which the liquid hydrocarbonproduct is removed to a receiver, the hydrogen-rich gas being removedthrough a water scrubber and recycled to the reactor. In order tocompensate for the quantity of hydrogen consumed within the process, andabsorbed by the normally liquid product efiiuent, fresh hydrogen isadded to the recycle gas as determined by the operating pressure withinthe reaction zone, in this instance, being in an amount of about 2,000s.c.f./bbl. For approximately onehalf of its effective, acceptable life,the catalytic composite will promote the-necessaryhydrogenation/hydrocracking reactions to produce a normally liquidproduct substantially free from pentane-insoluble asphaltene,organometallic contaminants, sulfurous and nitrogenous compounds. Thus,the normally liquid product effiuent will contain less than 0.5% byweight of pentane-insoluble asphaltenic material, less than 0.5 p.p.m.of organo-metallic compounds (calculated as elemental metals), less thanabout 50 p.p.m. of total nitrogen and less than about 0.50% by weight ofsulfur, the gravity, API at 60 F., of the liquid product effluent beingwithin the range of about 30.0 to about 32.0. As hereinbefore set forth,the presence of excessive quantities of pentane-insoluble ashaltenes aswell as organo-metallic compounds, interferes with the capability of thecatalyst to effect the destructive removal of nitrogenous and sulfurouscompounds. Therefore, the catalyst will indicate an activity declinethrough an increase in the concentration of residual sulfurous andnitrogenous compounds in the normally liquid product effluent. However,since the pentane-insoluble asphaltenes and organo-metallic compoundswill be within the previously determined range of less than 0.5% byweight and 0.5 p.p.m. respectively, the operation may be continued on aneconomic basis notwithstanding a comparatively high concentration ofresidual, nitrogenous and sulfurous compounds. In this situation, thenormally liquid product effluent is subjected to a second stageoperation at significantly more severe conditions for the purpose ofeffecting the complete destructive removal of the remaining sulfurousand nitrogenous compounds Thus, the method of the present invention isreadily adapted to a multiple-stage process which, as will be recognizedby those possessing skill within the art of petroleum refining, leadsdirectly to clean gasoline and diesel oil, the latter being sufiicientlydecontaminated to be used immediately as diesel, jet or fuel oil.

I claim as my invention:

1. A method of preparing a hydrorefining catalyst which comprises thesteps of:

(a) initially forming a refractory inorganic oxide carrier material, andcalcining said carrier material at a temperature above about 300 C.;

(b) impregnating the calcined carrier material with a decomposableorgano-metallic complex of a metal selected from the group consisting ofthe metals of Groups VB, VI-B and VIII of the Periodic Table;

(0) drying the impregnated carrier at a temperature below about 150 C.,and at which temperature the decomposition of said complex is avoided;

(d) thereafter decomposing said complex in the presence of ahydrocarbon.

2. The method of claim 1 further characterized in that said complex isdecomposed at a temperature within the range of from about 150 C. toabout 310 C., and in the presence of a hydrocarbon boiling at atemperature above about 650 F.

3. The method of claim 1 further characterized in that said decomposableorgano-metallic complex comprises an organo-molybdenum compound.

4. The method of claim 1 futher characterized in that said decomposableorgano-metallic complex comprises an organo-vanadic compound.

5. The method of claim 1 further characterized in that saidorgano-metallic complex comprises an organo-tungstic compound.

6. A method of preparing a hydrorefining catalyst which comprises thesteps of:

(a) initially forming an alumina-containing refractory inorganic oxidecarrier material, and calcining said carrier material at a temperatureabove about 300 C.;

(b) impregnating the calcined carrier material with a decomposableorgano-metallic complex of a metal selected from the group consisting ofthe metals of Groups VB, VI-B and VIII of the Periodic Table;

(c) drying the impregnated carrier material at a temperature within therange of from about C. to about C., and at which temperature thedecomposition of said complex is avoided;

(d) thereafter decomposing said complex at a temperature within therange of from about 150 C. to about 310 C., and in the presence of ahydrocarbon boiling at a temperature above about 650 F.

7. The method of claim 6 further characterized in that said decomposableorgano-metallic complex comprises a carbonyl.

'8. The method of claim 6 further characterized in that saiddecomposable organo-metallic complex comprises a heteropoly acid.

9. The method of claim 6 further characterized in that said decomposableorgano-metallic complex comprises a beta diketone.

10. The method of claim 6 further characterized in that said complex isdecomposed in a hydrogen sulfidecontaining atmosphere.

11. The hydrorefining catalyst prepared by the method of claim 1.

References Cited by the Examiner UNITED STATES PATENTS 2,450,675 10/1948Marisic et a1. 252-437 2,547,380 4/1951 Fleck 252437 3,156,641 11/1964Seelig et a1. 252437 DELBERT E. GANTZ, Primary Examiner.

S. P. JONES, Assistant Examiner.

1. A METHOD OF PREPARING A HYDROREFINING CATALYST WHICH COMPRISES THESTEPS OF: (A) INITIALLY FORMING A REFRACTORY INORGANIC OXIDE CARRIERMATERIAL, AND CALCINING SAID CARRIER MATERIAL AT A TEMPERATURE ABOVEABOUT 300*C,; (B) IMPREGNATING THE CALCINED CARRIER MATERIAL WITH ADECOMPOSABLE ORGANO-METALLIC COMPLEX OF A METAL SELECTED FROM THE GROUPCONSISTING OF THE METALS OF GROUPS V-B VI-B AND VIII OF THE PERIODICTABLE; (C) DRYING THE IMPREGNATED CARRIER AT A TEMPERATURE BELOW ABOUT150*C., AND AT WHICH TEMPERATURE THE DECOMPOSITION OF SAID COMPLEX ISAVOIDED; (D) THEREAFTER DECOMPOSING SAID COMPLEX IN THE PRESENCE OF AHYDROCARBON.